JP3895745B2 - Data transmission method, data reception method, data transmission system, transmitter and receiver - Google Patents

Description

  The present invention relates to a data transmission method, a data reception method, a data transmission system, a transmitter, and a receiver as a communication system used for mobile communication / mobile satellite communication.

  In mobile communication, the reception level fluctuates greatly (several tens of dB or more) due to the effects of distance deviation, shadowing, fading, and the like. One countermeasure is to perform level correction using AGC (Automatic Gain Control). FIG. 8 shows the overall configuration of the radio communication system, and FIGS. 9 and 10 show a transmitter and receiver of a conventional mobile radio communication system. For example, Non-Patent Document 1 or Non-Patent Document below is shown. 2.

  In FIG. 8, 1 is a transmitter that converts transmission data S1 into a radio signal, 2 is a transmission path through which the radio signal passes, and 3 is a receiver that extracts reception data S4 from the reception signal S3. In FIG. 9, 11 is a burst generation unit that generates a transmission burst S12 using transmission data S1 and information S11 from a preamble (repetitive pattern such as ALL0) addition unit 12, and 13 is a transmission burst S12. A modulating unit 14 for modulating is an antenna for skipping the modulated signal S13. Further, in FIG. 10, 31 is an antenna, 32 is a low noise amplifier (LNA), 33 is an R / F / I / F unit that converts the frequency of the amplified signal S31, and 34 is a low frequency. An AGC unit that makes the level (intensity) of the signal S32 constant, 35 is a demodulation unit that demodulates the AGC output S33, and 35 is a reception control unit that extracts the reception data S4 from the demodulated signal S34. In such a conventional wireless communication system, a repeating pattern such as ALL0 is adopted as a preamble pattern for AGC.

  Next, taking the following non-patent document 1 as an example, the operation of transmitting a signal from a mobile station (MS) to a base station (BMI: Base station, MSC and Interworking Function) will be described. The mobile station MS performs the AGC preamble (DATA: Sync, Synchronization + SYNC +: Additional Synchronization) along with the AGC preamble (DATA, error correction encoded data) in the burst generator 11. PREAM: Preamble) is added to form a transmission burst. FIG. 11 shows the configuration of the burst. In Non-Patent Document 1 below, as a preamble pattern, π / 4 shift modulation in which transmission data is a repetition of “1” and “0” is added for 8 symbols.

  FIG. 12 shows the phase state of each symbol in the preamble. In this case, the preamble portion has a constant envelope level. The signal S12 output from the burst generation unit 11 is modulated by the modulation unit 13, amplified, and then radiated from the antenna 14. When passing through the transmission path 2, the radio signal is affected by fading (Rayleigh fading, frequency selective fading, etc.), and the waveform is greatly distorted. In addition, the reception level varies greatly due to the distance between the base station BMI and the mobile station MS, shadowing, and fading. A signal received by the antenna of the base station BMI is amplified by the LNA 32 and converted to a low frequency by the R / F / I / F unit 33. An input unit of the demodulating unit 35 includes an A / D converter and the like, and the input signal needs to be within a certain range. However, since the output of the R / F / I / F unit 33 includes a large level deviation, the level is corrected by the AGC unit 34 before being input to the demodulating unit 35 and adjusted to a constant level. This signal S34 is demodulated by the demodulator 35, and then the data part is extracted from the burst by the reception controller 36, subjected to processing such as error correction, and then output as received data S34.

  The operation of the AGC unit 34 that performs level correction will be described. FIG. 13 shows a basic configuration of the AGC 34. An input signal (low frequency signal) S32 to the AGC unit 34 including a large level deviation is amplified or attenuated by an AGC amplifier 41 to become an AGC output S33. The AGC output S33 is simultaneously input to the level detection unit 42, compared with a predetermined reference value, and a signal indicating the difference between the reference value and the AGC output S33 is output. This signal is subjected to an AGC amplifier control voltage (RSSI: Received Signal Strength Indicator) S40 that determines the amplification ratio of the AGC amplifier 41 after fine fluctuations are removed by a low pass filter (LPF) 43, The AGC amplifier 41 is controlled so that the AGC output approaches the reference value. Since the AGC unit 34 performs the above-described operation, a certain time is required for the closed loop including the AGC amplifier 41, the level detection unit 42, and the LPF 43 to converge before the AGC output S33 is stabilized. In the following non-patent document 1, as shown in FIG. 14, the AGC is converged at the preamble portion near the head of the burst, and the AGC output level (demodulator input level) of the SYNC and DATA portions that follow is within a desired range. This makes it possible to perform good demodulation.

“TIA / EIA / IS-136.1-A” (TIA / EIA) INTERIM STANDARD: TDMA Cellular / PCS-Radio Interface-Mobile Station-Base Station-Compatibility-Digital Control Cannel) “RCR STD-32”

  As described above, when a fixed repetitive pattern is employed in the AGC preamble, there is a problem that AGC does not operate satisfactorily in a transmission path in which frequency selective fading occurs. This is particularly noticeable when the symbol rate is fast with respect to the fading speed and the fading state does not change during the preamble. Frequency selective fading will be described. Frequency selective fading occurs when the delay amount of the delayed wave reflected from a distant building, mountain, or the like cannot be ignored compared to the symbol period, as shown in FIG.

  For example, there is a case where selective fading is used when there is a delay amount of about 1/10 symbol or more. At this time, as shown in FIG. 16, if no countermeasure is taken, an error occurs in the determination of the received signal due to interference between the preceding wave and the delayed wave. Further, as shown in FIG. 17, the signal spectrum of the combined wave of the preceding wave and the delayed wave is a distortion of the spectrum of the transmission signal, which is the origin of the name “frequency selective fading”. As is clear from the above description, frequency selective fading is more likely to occur on the same transmission path as the information speed is higher, that is, as the symbol rate is higher.

  In a system that employs a simple fixed pattern repetition as an AGC preamble pattern, when frequency selective fading occurs in the transmission path, the average received power of the preamble portion varies greatly depending on the phase relationship between the preceding wave and the delayed wave. FIG. 18 shows the phase relationship between the preceding wave and the delayed wave, and the combined wave at that time. Times 1, 2, and 3 represent three consecutive symbols. When the preamble pattern is a fixed pattern repetition, the phase relationship between the preceding wave and the delayed wave is constant, and if the transmission rate is sufficiently large relative to the fading rate, the same relationship is considered to be maintained during preamble reception. In FIG. 18, when the preceding wave and the delayed wave cancel each other ((1) (2) (3)), when they do not influence each other very much ((4) (5) (6)), when they strengthen each other ((7 ) (8) (9)) are shown, but the phase relationship is determined by the delay amount of the delayed wave, and therefore changes randomly every moment as the mobile station MS moves. For this reason, the average received power varies greatly from time to time.

  On the other hand, when a random pattern is received (the data portion is considered to be a nearly random pattern due to scramble or the like), the phase relationship between the preceding wave and the delayed wave also changes within the same burst. For this reason, as shown in FIG. 19, when the preceding wave and the delayed wave strengthen each other in the same burst, the cases where they cancel each other occur randomly, and if the entire burst is averaged, a constant received power can be obtained.

  Therefore, in the system in which the AGC is converged in the preamble portion as described above and the AGC output of the subsequent data portion is made constant, a large difference appears between the received power of the preamble portion and the received power of the data portion. Is not made. FIG. 20 shows how the AGC operates at this time. When there is a large difference in received power between the preamble portion and the subsequent data portion (including SYNC), an appropriate output level cannot be obtained in the data portion even if the AGC converges ((1)) in the preamble. Until the AGC outputs a signal in the vicinity of the reference value, the AGC needs to converge again ((3)). During this time, the data ((2)) cannot be demodulated properly.

  The present invention has been made to solve the above-described problems. Even in a transmission line in which frequency selective fading occurs, good level control (AGC) and appropriate level detection are realized to enable good communication. An object of the present invention is to provide a data transmission method, a data reception method, a data transmission system, a transmitter, and a receiver.

  In order to solve the above-described problems and achieve the object, in the data transmission method according to the present invention, the transmission side adds control data to the transmission data, modulates it with a predetermined modulation method, and transmits it as a transmission signal. A data transmission method in a data transmission system in which a reception side detects reception signal strength using the control data in the transmission signal, wherein the reception power detection section for detecting the reception power strength is the transmission data. And using a wideband spectrum signal in the received power detection section, and further transmitting the transmission data for each burst, the wideband spectrum signal of one burst for one or a plurality of transmission data It is characterized by adding.

  In the data transmission method according to the next invention, control data is added to the transmission data on the transmission side, modulated by a predetermined modulation method and transmitted as a transmission signal, and the control data in the transmission signal is transmitted on the reception side. A data transmission method in a transmitter used in a data transmission system that detects a received signal strength using a receiver, wherein a reception power detection period for detecting the received power strength is arranged before the transmission data, and A broadband spectrum signal is added to the reception power section, and when transmitting the transmission data for each burst, the broadband spectrum signal of one burst is added to one or a plurality of transmission data.

  In the data transmission method according to the next invention, a signal having a period equal to or greater than the maximum delay time of the delay wave of the transmission path assumed in the propagation path model of the corresponding system is used as the broadband spectrum signal. And

  In the data transmission method according to the next invention, control data is added to the transmission data on the transmission side, modulated by a predetermined modulation method and transmitted as a transmission signal, and the control data in the transmission signal is transmitted on the reception side. A method of receiving data in a receiver used in a data transmission system that detects received signal strength using a receiver, wherein a received power detection section for detecting the received power strength is located before the transmitted data on the transmitting side. And a broadband spectrum signal is added to the received power detection period, the received power intensity is detected in the received power detection period, and the received signal intensity is detected in the received power detection period using the received power intensity. The gain control is converged, and the reception power of subsequent transmission data is adjusted to the vicinity of the reference value.

  In the data transmission method according to the next invention, a signal having a period equal to or greater than the maximum delay time of the delay wave of the transmission path assumed in the propagation path model of the corresponding system is used as the broadband spectrum signal. And

  In the data transmission system according to the next invention, the transmission side adds control data to the transmission data, modulates the transmission data with a predetermined modulation method, and transmits it as a transmission signal. The reception side transmits the control data in the transmission signal. In the data transmission system that detects the received signal strength using the received power detection section for detecting the received power intensity is arranged before the transmission data, and a wideband spectrum signal is used in the received power detection section, Furthermore, when transmitting the transmission data for each burst, the wideband spectrum signal of one burst is added to one or a plurality of transmission data.

  In the data transmission system according to the next invention, as the broadband spectrum signal, a signal having a period longer than the maximum delay time of the delay wave of the transmission path assumed in the propagation path model of the corresponding system is used. And

  In the transmitter according to the next invention, the control data is added to the transmission data on the transmission side, modulated by a predetermined modulation method and transmitted as a transmission signal, and the control data in the transmission signal is transmitted on the reception side. A transmitter in a data transmission system for detecting received signal strength using a received power detection period for detecting the received power strength arranged in front of the transmitted data, and a broadband spectrum signal in the received power interval In addition, when transmitting the transmission data for each burst, the wideband spectrum signal of one burst is added for one or a plurality of transmission data.

  In the transmitter according to the next invention, as the broadband spectrum signal, a signal having a period longer than the maximum delay time of the delay wave of the transmission path assumed in the propagation path model of the corresponding system is used. To do.

  In the receiver according to the next invention, the control data is added to the transmission data on the transmission side, modulated by a predetermined modulation method and transmitted as a transmission signal, and the control data in the transmission signal is transmitted on the reception side. And a receiver used in a data transmission system for detecting received signal strength, wherein a reception power detection section for detecting the received power strength is arranged before the transmission data on the transmission side, and When a broadband spectrum signal is added to the received power detection period, the received power intensity is detected during the received power detection period, and gain control of the received signal is converged during the received power detection period using the received power intensity. The reception power of the subsequent transmission data is adjusted to the vicinity of the reference value.

  In the data transmission method according to the next invention, a signal having a period equal to or greater than the maximum delay time of the delay wave of the transmission path assumed in the propagation path model of the corresponding system is used as the broadband spectrum signal. And

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIG.
FIG. 1, in which the same reference numerals are assigned to the parts corresponding to those in FIG. 9, shows the transmitter of the radio communication system according to the first embodiment of the present invention. In the figure, 11 is a burst generator for generating a transmission burst S52 using transmission data S1 and information S51 from a preamble (random pattern) adding unit 51, 13 is a modulator for modulating the transmission burst S52, and 14 is This is an antenna for skipping the modulated signal S53. The overall configuration of the wireless communication system and the configuration of the receiver are the same as those of FIGS. 8 and 10 described above. However, in the case of the first embodiment, the transmission line 12 in FIG. 8 is a frequency selective fading transmission line.

  The operation of the first embodiment will be described. The burst generator 11 adds an AGC preamble (random pattern) to the data (DATA) to be transmitted on the transmission side along with a ramp (R), a synchronization word (SYNC) bit, etc., for example, as shown in FIG. A credit burst S52 is generated. The transmission burst S52 is modulated by the modulation unit 13 and then transmitted from the antenna 14. The transmission signal S2 transmitted from the transmission side is subjected to frequency selective fading in the transmission path 2 and input to the antenna 31 on the reception side. The input signal is amplified by the LNA 32 and converted to a low frequency signal S32 by the R / F • I / F unit 33. Since the output of the R / F / I / F unit 33 includes a large level deviation, the power level is adjusted by the AGC unit 34 and then input to the demodulator 35, and thus the received data S4 is extracted.

  FIG. 3 shows a probability density distribution of received power when two QPSK-modulated waves (leading wave power 1, delayed wave power 0.5) interfere with each other with a random phase difference. M series was adopted as the random pattern. As can be seen from the figure, when the random pattern is received, the power is almost constant, whereas when the ALL0 pattern is received, the received power has a large deviation, and a large mismatch occurs between the two. Probability is high.

  According to the first embodiment, by adopting a random pattern for the preamble, a large difference in received power level does not occur between the preamble part and the data part, and even when a signal subjected to frequency selective fading is received, As shown in FIG. 2, the AGC converges to an appropriate value in the preamble portion ((1)), and the level of subsequent data can be adjusted to the vicinity of the reference value.

  Note that the random pattern added by the preamble adding unit 51 is not limited to the M sequence, and the same effect can be obtained unless the length is equal to or shorter than the maximum number of delay waves in the transmission path. In other words, the same effect can be obtained if the modulation spectrum of the preamble portion is not a bright line spectrum but a random pattern having a wide spectrum.

Embodiment 2. FIG.
FIG. 4 in which the same reference numerals are assigned to the corresponding parts to FIG. 1 shows a transmitter of the wireless communication system according to the second embodiment of the present invention, and FIG. 5 in which the same reference numerals are assigned to the corresponding parts to FIG. The structure of AGC in the receiver of the radio | wireless communications system which is Embodiment 2 of this invention is shown. In FIG. 4, 60 is a data burst generator for generating a data burst S62. Reference numeral 61 denotes a random pattern generation unit that generates the AGC random pattern S60, and reference numeral 62 denotes an AGC burst generation unit that generates the AGC burst S61. Reference numeral 63 denotes a switch for switching transmission bursts, which determines which one of AGC burst S61 and data burst S62 is to be transmitted. On the other hand, in FIG. 5, 70 is a memory for storing the output S40 of the LPF 43 as the AGC amplifier control voltage S40A, and 71 is a switch for determining whether or not the output S40 of the LPF 43 is sent to the memory 70. In addition, the whole radio | wireless communications system and the structure of a receiver in this embodiment are the same as that of FIG. 8, FIG.

  The operation of the second embodiment will be described. On the transmission side, the AGC burst generation unit 62 generates the AGC burst S61 using the AGC random pattern S60 output from the random pattern generation unit 61. The data burst generator 60 generates a data burst S62 using the transmission data S1. These bursts are selected by the switch 63 in accordance with a predetermined procedure, modulated by the modulator 13 and then transmitted from the antenna 14. The transmission signal S2 undergoes fading on the transmission path 2, and then is input to the receiver 3, where amplification and frequency conversion are performed to obtain an AGC input signal S32.

  During the AGC burst reception, the switch 71 in the AGC loop is turned on, and the AGC amplifier control voltages (RSSI) S40 and S40A converge so that the AGC output S33 becomes the reference value. Thereafter, when receiving the data burst, the switch 71 is turned off, and the value converged when the AGC burst is received and stored in the memory 70 is used as the value of the AGC amplifier control voltage (RSSI) S40A.

  According to the second embodiment, if the state change of the transmission line 2 is small between the reception of the AGC burst and the reception of the data burst, the same value can be used as the value of the AGC amplifier control voltage (RSSI) S41. When receiving the burst, the AGC output S33 at an appropriate level can be obtained from the beginning of the burst. As a result, both the subsequent demodulator 35 and the reception controller 36 can operate appropriately, and receive data can be obtained as a good demodulation result. Note that the correction of the value of the AGC amplifier control voltage (RSSI) S40A may be continued by turning on the switch 71 even during data burst reception.

Embodiment 3 FIG.
6 in which the same reference numerals are assigned to the parts corresponding to those in FIG. 10 shows a receiver of the wireless communication system according to the third embodiment of the present invention. In this case, level detectors 80A and 80B corresponding to the AGC unit from antenna 31 are shown. The system is composed of two receivers, and each system is associated with an English letter “A” or “B”. That is, in the figure, 80A and 80B are level detection units that measure the reception power level and output the reception level information S80A and S80B, and 81 is a reception state from the reception level information S80A and S80B of the plurality of level detection units 80A and 80B. The determination unit 81 selects the best one, 82 is a switch driven by a control signal S81 from the determination unit 81, and S82A and S82B are reception signals after passing through the level detection units 80A and 80B. The whole radio communication system and the configuration of the transmitter in the third embodiment are the same as those in FIGS.

  Next, the operation of the third embodiment will be described. The receiving side receives the radio waves transmitted from the transmitter with the two antennas 31A and 31B. The received signals are amplified and frequency-converted, and are input to the level detectors 80A and 80B. Level detectors 80A and 80B detect the power levels of signals S32A and S32B, and send reception level information S80A and S80B to determination unit 81. Although various forms can be considered for the level detection units 80A and 80B, for example, when AGC is used, the RSSI signal becomes reception level information.

  The determination unit 81 compares the reception level information S80A and S80B from the two level detection units 80A and 80B, controls the switch 82 by the control signal S81, and receives the signal received from which antenna 31A or 31B to the demodulation unit 35. Decide whether to enter. When the format described above with reference to FIG. 11 is used as the burst format, if the determination unit 81 is operated during the AGC preamble reception and the switch 82 is fixed, a reception signal more suitable for reception of the data portion can be selected, and reception performance can be selected. Can be improved. Also in the third embodiment, it is an absolute condition to predict the received power intensity of the data portion in the preamble portion.

Embodiment 4 FIG.
FIG. 7 shows a burst format according to the fourth embodiment of the present invention. In a system in which RSSI of AGC is determined using power information of a burst received in the past, the AGC pattern does not need to be at the head of the burst, but is arranged in the midamble as shown in FIG. 7 or behind the burst. The same effect can be expected with the postamble. Preamble, midamble and postamble may be used together.

Embodiment 5 FIG.
In a mobile station that receives radio waves from a plurality of base stations, the present invention can be used to determine a base station for communication. That is, it is possible to perform level detection by using an AGC preamble or an AGC burst having a random pattern, select an optimal base station, and set a line. This selection may be performed while receiving a specific line.

  As described above, the data transmission method, data transmission system, transmitter and receiver according to the present invention are useful for communication systems used for mobile communication / mobile satellite communication.

It is a block diagram which shows the structure of the transmitter of the radio | wireless communications system which is Embodiment 1 of this invention. It is a basic diagram with which it uses for description of the structure of the burst for transmission produced | generated by the transmission side. It is a graph with which it uses for description of probability density distribution of received power when two waves which carried out QPSK modulation interfere with a random phase difference. It is a block diagram which shows the structure of AGC of the transmitter of the radio | wireless communications system which is Embodiment 2 of this invention. It is a block diagram which shows the structure of AGC of the receiver of the radio | wireless communications system which is Embodiment 2 of this invention. It is a block diagram which shows the structure of the receiver of the radio | wireless communications system which is Embodiment 3 of this invention. It is a basic diagram with which it uses for description of the burst format in Embodiment 4 of this invention. It is a block diagram which shows the whole structure of a radio | wireless communications system as a premise of this invention. It is a block diagram which shows the structure of the conventional transmitter within the radio | wireless communications system of FIG. It is a block diagram which shows the structure of the conventional receiver in the radio | wireless communications system of FIG. It is a basic diagram which shows the structure of the burst for transmission which added the preamble for AGC. FIG. 12 is a schematic diagram for explaining a phase state of each symbol in the preamble of FIG. 11. It is a block diagram which shows the basic composition of the conventional AGC. It is an approximate line figure used for explanation of a processing procedure of AGC. It is a basic diagram with which it uses for description of generation | occurrence | production of frequency selective fading. It is a basic diagram with which it uses for description of the error generation in frequency selective fading. FIG. 6 is a signal spectrum distribution diagram showing a transmission signal and a reception signal when frequency selective fading occurs. It is a basic diagram with which it uses for description of the phase relationship of the preceding wave, delay wave, and synthetic wave at that time in case frequency selective fading occurs in a transmission line. It is an approximate line figure used for explanation when a preceding wave and a delayed wave strengthen and cancel each other within the same burst. It is a basic diagram provided for description when there is a difference in received power between a preamble portion and a subsequent data portion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmitter 2 Transmission path 3 Receiver 11 Burst production | generation part 12 Preamble addition part 13 Modulation part 14 Antenna 31, 31A, 31B Antenna 32, 32A, 32B Low noise amplifier 33, 33A, 33B R / F / I / F part 34 AGC Unit 35 demodulation unit 36 reception control unit 41 AGC amplifier 42 level detection unit 43 low pass filter 51 preamble addition unit 60 data burst generation unit 61 random pattern generation unit 62 AGC burst generation unit 63 switch 70 memory 71 switch 80 level detection unit 81 Judgment part 82 switch

Claims (6)

On the transmission side, transmitted as pressure and send signals with the preamble for detecting reception power intensity in the receiver side to the transmitting data, the receiving side detects the reception power intensity by use of the preamble in the transmission signal A data transmission method in a mobile radio communication system,
A preamble for detecting reception power intensity in the receiver side is arranged in front of the transmission data, and Ru using a random pattern on the preamble,
Data transmission method in a mobile radio communication system comprising a call. On the transmission side, transmitted as pressure and send signals with the preamble for detecting reception power intensity in the receiver side to the transmitting data, the receiving side, a reception power intensity by use of the preamble in the transmission signal A data transmission method in a transmitter used in a mobile radio communication system to detect,
A preamble for detecting reception power intensity in the receiver side is arranged in front of the transmission data, and Ru using a random pattern on the preamble,
Data transmission method according to claim and this. On the transmission side, transmitted as pressure and send signals with the preamble for detecting reception power intensity in the receiver side to the transmitting data, the receiving side, a reception power intensity by use of the preamble in the transmission signal A data reception method in a receiver used in a mobile radio communication system to detect,
On the transmission side, a preamble for detecting the received power intensity is arranged before the transmission data, and the transmission signal in which random data is used for the preamble is received ,
A data receiving method, wherein the received power intensity is detected by the preamble . On the transmission side, transmitted as pressure and send signals with the preamble for detecting reception power intensity in the receiver side to the transmitting data, the receiving side detects the reception power intensity by use of the preamble in the transmission signal In a mobile radio communication system,
A preamble for detecting reception power intensity in the receiver side is arranged in front of the transmission data, and Ru using a random pattern on the preamble,
Mobile radio communication system comprising a call. On the transmission side, transmitted as pressure and send signals with the preamble for detecting reception power intensity in the receiver side to the transmitting data, the receiving side, a reception power intensity by use of the preamble in the transmission signal A transmitter used in a mobile radio communication system to detect,
A preamble for detecting reception power intensity in the receiver side is arranged in front of the transmission data, and Ru using a random pattern on the preamble,
Transmitter which is characterized a call. On the transmission side, transmitted as pressure and send signals with the preamble for detecting reception power intensity in the receiver side to the transmitting data, the receiving side, a reception power intensity by use of the preamble in the transmission signal A receiver used in a mobile radio communication system to detect,
On the transmission side, a preamble for detecting the received power intensity is arranged before the transmission data, and the transmission signal in which random data is used for the preamble is received ,
A receiver characterized in that the received power intensity is detected by the preamble .

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